A criminal investigation was launched on May 3, 2011, after Limerick GP Dr Richard O'Flaherty accused Det Supt Jim Browne and Sgt Andrew O'Riordan of refusing him access to a patient who was being questioned in Henry Street station about a gangland murder.
The doctor also claimed he was threatened by Det Supt Browne, alleging that he was told he would not draw his pension if he returned to the garda station.
The investigation was launched under Section 98 of the Garda Siochana Act, 2005.
The complaint dated to February 23, 2010, when Dr O'Flaherty went to the garda station and demanded to see his patient, John Coughlan.
Coughlan was at that time being questioned about the murder of a bread delivery man in the city.
Earlier that morning, Coughlan shot Daniel Treacy (35) four times at close range with a Glock automatic pistol in a Topaz garage as he made a delivery around 6am.
Coughlan, who had never been in trouble with the gardaí before, then went looking for two other men with the intention of also killing them but didn't find them.
The attack was in revenge for the murder of his younger brother Darren. Darren was kicked to death by Daniel Treacy's brother Richard and his cousin Joseph Keane in 2005.
Coughlan, a 31-year-old electrician, has since been convicted of murder.
In a letter dated May 12 last, GSOC said that Dr O'Flaherty had not been requested to attend by either the gardaí or his patient, Coughlan.
It continued: "Mr Coughlan had already been seen by two other doctors and as such there was no necessity for Dr O'Flaherty to see Mr Coughlan.
"If Dr O'Flaherty had any concerns about the aptitude of his medical colleagues who had seen Mr Coughlan, he could have contacted them directly to inform them of his concerns and update them on Mr Coughlan's medical history if required."
GSOC also found that there was no evidence to substantiate the second allegation about Det Supt Browne's alleged comments about Dr O'Flaherty's pension.
The allegations were raised in the Dáil by Roscommon TD Luke 'Ming' Flanagan and Finian McGrath, who accused gardaí in the city of engaging in "the most serious, degrading and intimidating treatment" of those in custody.
In a submission to the Dáil Justice Committee on May 14 last year, Dr O'Flaherty referred to the same incident.
It said: "I suggest that all patients be entitled to their doctor of choice when in custody and it should be a criminal offence for a garda to refuse that, with the matter also to be reported to the Garda Síochána Ombudsman Commission."
The Irish Independent was unable to contact Dr O'Flaherty for comment.
In 2005, a judge branded the doctor "arrogant" when he came before the district court charged with failing to provide a breath sample to gardaí when he was arrested on suspicion of drunk driving.
Judge Tom O'Donnell banned him from driving for two years and also fined him €600 for failing to provide a breath sample to gardaí.